Kiln for the manufacture of charcoal



2 Sheets-Sheet 1.

(No Modl.)

H. MPIBROE.

KILN FOR THE MANUFACTURE OF CHARCOAL.

Patented NOV. 23

N. PETERS. Pholoulhographur, Washillglun. D. C

(No Model.) 2 Sheets-Sheet 2.

H. M. PIERCE.

KILN FOR THE MANUFACTURE OF CHARCOAL. No. 852,931. Patented Nov. 23, 1886.

Nv PETERS, Phnmmhogrmphur. Wnhinglon D. C. v

UNITED STATES PATENT D r-rice.

HENRY M. PIERCE, OF NASHVILLE, TENNESSEE.

KILN FOR THE MANUFACTURE OF'CHARCOAL.

- SPECIFICATION iorming part of Letters Patent No. 352,931, dated November 23, 1886.

Application filed January 11, 1886. Serial No. 188,233. (No model.)

To all whom it may concern:

Be it known that I, HENRY M. PIERCE, a citizen of the United States, residing at Nash: ville, in the county of Davidson and-State of Tennessee, have invented certain new and useful Improvements in Kilns for the Manufacture of Charcoal; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, wherein- Figure 1 is a vertical section of a meiler, showing the preferred form of devices employed by me in applying my invention. Fig. 2 is a plan view of the same. Fig. 3 is an enlarged detail perspective view of several sections or plates which form the rigid breast shown in Figs. 1 and 2. Fig. 4 is a transverse vertical sectional view of one of said plates. Figs. 5, 6, 7, and 8 are details showing how the rigid breast or base section of a meiler may, if desired, be made of brick or stone; and Fig. 9 isa plan showing how several 'meilers may be combined to form a plant with great saving of space, material, and help required to tend the same.

Like letters refer to likcparts wherever they tion and operation of meilers or charcoal-pits for the carbonization of wood, and has for its object to retain all the advantages of the old and well -known meiler, as well as the features of its construction, which adapt it for use in the forests, and to obtain all the advantages of the kiln and retort systems, which are now only attainable at great expense for plants that are, not adapted for forest use.

To this end the invention consists, generally stated, in providing a meiler with a rigid breast or base section, and retaining above said breast or base section the usual air-tight covering of earth, leaves, sod, &c., whereby the air and gas ports may be preserved intact and opened or closed at will, while the cover will sink with carbonizing wood, confine the heat to carbonizing mass, and prevent loss of heat by radiation or the unequal progress of the process at different points in the charge.

In order that the nature and advantages of my invention may be fully understood, it will kiln processes and point out the advantages and disadvantages of each.

The oldest-and most commonly practiced process is what is known as the "meiler, which is especially adapted for use in the forests. It may be briefly stated to consist in stacking wood around a central pole, to which every piece of wood inclines or points, so that when the heap is completed two, or sometimes three, ranks deep the meiler presents an oval appearance from the base to the top, or in a measure resembles a hemisphere. The pile is then covered with leaves, straw, sodding, soil, or mold, 8m, and on this covering earth is thrown to the depth of four to six inches.

Fire is communicated to the central part of r the stack through an opening in the bottom left for the purpose, and holes are made in the covering of the wood to admit air to support combustion, and other holes for the escape of vapors, gases, 850.

The advantages of the meiler process are that as carbonization advances and the mass shrinks the coveringsettles with it, prevents the accumulation .of gases, &c., at the top of the pile, prevents radiation and loss of heat from the mass, confines the heat to the space where carbonization is going on, and, as a re sult, produces a better or more solid charcoal. Furthermore, the meiler is inexpensive in construction, adapted for forest use, and thus avoids the cost of hauling the wood. Its disadvantages are that from the beginning to the end of the charring process much difficulty is experienced in keeping open the air and gas holes, (owing to constant caving of the covering,) and that constant care and labor are involved for that purpose. The closing of the air and gas ports causes the carbonization to go on with more or less irregularity and unevenness in all parts of the meiler, producing irregular and uneven outward surfaces, and often large cavities, which have to be filled with fresh wood to prevent the general destruction of the-entire heap. Furthermore, if

the weather is unfavorable, there is great liability of losing either the wood or the charcoal, in spite of the closest attention and care. The disadvantages of the meiler process gave rise to the use of kilns.

The kilns or ovens, which are usually circu-' IOU lar or oblong, with nearly-perpendicular sides and arched top, are of brick or stone, are provided with air-ports in the lower part of the vertical walls for admission of air to support combustion, and ports above for the es cape of vapor, gases, &c. These kilns or ovens, which are of a permanent nature, and generally arranged in groupsa plant or battt-ry necessitate the transporting of the wood to the kiln or oven, are expensive to construct and maintain, and are not adapted to forest use.

The advantages of the kilns or ovens are that they enable the collier to provide regular air and gas ports, so as better to maintain and control the charring process, enable the vapors and gases given off from the charge to be collected and utilized, if desired, avoids all risks of loss of wood or charcoal from stress of weather, and reduces the number of open atives required. The disadvantages of the kilns and ovens are, first, the cost of erecting and maintaining the same, principally due to the-arched cover or top; secondly, in the opera tion of kilns or ovens the arched rigid top re mains stationary, so that as the charge gradu ally sinks lower and lower in the kiln a constantly-increasing heat-space is made, which not only withdraws the greatest heat from the uncharred portion in the lower part of the,

kiln, but becomes a radiator of heat through the walls and roof of the oven; thirdly, the withdrawing of the heat from the bottom of the kiln retards the charring processin proportion as it approaches the bottom of the kiln, and renders it exceedingly difficult, and at times almost impossible; and, finally, the efforts to force the charring to the lowest part of the kiln result in exposing the charcoal already made in the upper portlons of the mass to such an excessive heat asto greatly depreciate its value.

Having briefly reviewed the art and indicated the objects I desire to effect, I will next suitable rigid material.

point out broadly the application of my invention, so that its scope can be ascertained, and then will specifically describe what I believe to be the best available means.

1 construct the meiler in the ordinary way, and before applying the leaves and earth covering of the wood 1 surround the entire heap at its base with a breastwork of iron plates,

(see Figs. 1, 2, 3, and 4,) brick laid dry or in mortar, (see Fi 5,) stone-work laid dry or in mortar, (see Fi 6,) or blocks of terracotta,-concrete, (see Figs. 7 and 8,) or other The height of this breastwork or rigid lower covering portion of the meiler will be in proportion to the height of the meiler; but for meilers of the ordinary height the best results are found when the height of the breastwork is from three (3) to four (4) feet, and it is inclined inward with the wood, as shown in the drawings accompa nying this specification.

The rigid girdle which incloses the heap is provided at intervals near the bottom of the stack 01' pile with a series of air-ports, to admit the air to support combustion, and near the top of the breastwork are a series of ports or passages for the escape of vapors or gases given oli' during the desiccation and carbonization of the wood. In case the breastwork is formed of brick, stone-work, concrete, or terracotta blocks, the ports for air and gas may be formed by inserting terra-cotta or other suitable piping. These air and gas ports .will be provided with suitable bricks or stoppers, and it it is desirable to save the vapors and gases the ports forthe escape thereof may be connected by suitable piping with receivers, condensers,absorbers, Ste.

A breastwork of the character specified can be thrown around the heap in ashort time, and removed as quickly after the carboniza' tion has been completed. After the base of the pile has received this rigid covering, leaves, straw, earth, the, are added, as is now commonly practiced in covering meilers, to complete the covering of the heap above the rigid breastwork. Fire is communicated to the mass, more or less of y, the air-holes around the base of the breast are opened, and as the operation continues more or less gasoutlets are opened. As the coaling proceeds the top of the meiler is first coaled, and as the mass shrinks and sinks the covering will follow it, preventing the formation of wasteheat chambers in the upper part of the heap. To prevent openin s in the covering of the meiler, it can be thickened, strengthened, and kept intact by additional earth coverings as it gradually settles down, following the settling of the wood and the escape of gas. As the escaping gas and entering air pass only through the proper openings in the rigid breastwork, the covering, will remain intact and impervious to the end of the process. The vapors and gases, having at all times free escape through the pervious vents of the breastwork, do not. force their way through the cap covering and thus aid in its destruction. hen the coal ing is completed, the openings are all thoroughly closed, and when the coal is ready to be taken out a part of the wall is removed and the coal raked out in the usual manner. The material of the top covering and the breast-wall can be used over and over again.

Among the valuable features of my invention are that it has all the advantages of the meiler process, which renders it adapted to use in the forest and results in the production of the most solid and best quality of charcoal, while it is not subject to the disadvantages of the tedious labor incident to making and covering vent-holes over and over again, as commonly practiced in meilers; neitheris it liable to the losses resulting from the irregular sinking in or sliding off of the coverand from the operation of unfavorable weather, and there are many other advantages which could be enumerated but need not, as they will be at once apparent to the practical collier.

1 would finally point out a specific construction of the rigid breastwork, which for portabilityand ready application seems to me to be the most desirable means for carrying out my invention, andfor this purpose I will refer to Figs. 1, 2, 3, and 4 of the drawings. In said figures, a indicates a foundation or paving of puddled clay, concrete, brick, or stone, which may be laid under the rigid breast or retaining-wall, and upon which the wood is stacked in ranks or tiers, in the usual manner for forming meilers, and then surrounded at. its base with the rigid breastwork.

b indicates a sectlon of the preferred form of rigid breast, which is of iron plating, either lapped for bolting together, or, as shown, provided with vertical flanges c for a like purpose. These sect-ions orarcsb may havea base-flange, d, and cap-flange e, and, by preference, the arc is less above than below, so that when in position the section b will incline or lean against the heap. At intervals near the base-flange d or bottom of the section are air-portsf, which may have inwardly projecting shield (or flange) g, to prevent the closing or clogging of the air-ports from within, and-plug-shelf h, to support the brick, or its equivalent, which is used for a plug or stopper to close the air-port at will. I

t indicate the vapor or gas vents, which are arranged near the top flange, 'e, and are provided with inwardly-projecting shields k and outwardly-projecting plug-shelf l, for the same 7 purposes as in the case of the air-ports before referred to.

In the drawings the air and gas ports of plates b are shown as in single tiers; but it is evident that there may be any number of tiers desired. The sections b, of plate-iron, are arranged or set up around the base of the meiler and bolted together, after which the joints may be luted, if desired. When the coaling process is completed, any one or more plates or sections b can be upbolted and removed for gaining access to the pit and removing the coal.

' plates, when separated, may be packed in comparatively small compass.

Bybuilding the meiler in oblong form with corresponding breastwork and cross or partition wallsm, as shown in the plan view, Fig. 9, a large number of'meilers can be concentrated in one spot, if required, and the force of colliers can be proportionately decreased, and a battery of meilers can be established in the heart of aforest, where the wood is in abundance.

I am aware that a low hurdle of wickerwork or Wattles has heretofore been woven around the foot of an earth-covered meiler to defend the same from injury by wash or stress of the weather, and also to assist in keeping the base of the meiler pervious for the entrance of air, and do not herein claim the same,

vsu-med in the central fire-chamber, and I do not For transportation, thefor the reasons that it provides no means for controlling the entrance of air or exit of vapors and gases, is a destructible matter which has to be renewed with each meiler, and in no manner subserves the purpose of a rigid breastwork, as hereinbefore set forth, which latter is, ,in fact, the economic combination of the old-fashioned meiler with the modern kiln or oven, so as to preserve the advantages of both, and increase the quantity and improve the quality of the product.

I am also aware that a meiler for carbonizing peat by means of a central fire sustained by the gases distilled from the peat has been constructed with acentral grate, fire-cage, or fire-chamber, with air-ducts leading thereto, and with an outer breastwork of iron plates bolted together, and having small airports at or near the base of the plates, and a cap or covering of earth, &c., wherein the air enteredaround the base of'the meiler, and the gases, 850., distilled from the peat, were conherein claim the same; but,

Having thus set forth the nature and advantages of my invention, fully indicated its scope, and also pointed out the best means now known to me for applying the invention, I claim 1. As an improvement in the construction of movable or forest meilers, a rigid removable base-section or breastwork having airports and gas-vents, and asoil or similar capsection, substantially as and for the purposes specified. I

2. A rigid breast for forest or movable meilers, having regular or fixed air-ports and gasforest-meilers, said section consisting of an 1x5 iron plate provided with ports and stopper shelves, substantially as and for the purposes specified.

In testimony whereof I afflx my signature, in presence of two witnesses, this 23d day of I20 November, 1885. I

HENRY M." PIERCE.

Witnesses:

E. V. FALOONNER, J oHN MoRRow. 

